Draw and label the root morphology of the following samples.
Compare and discuss the
differences between the two types of root:
i. Zea mays
- Zea mays is a fibrous root systems where located closer to the surface and have many
small roots that spread out laterally from the base of the stem. Development of tap
root stip growing leaving fibrous root. Fibrous root systems can help prevent soil
erosion. Fibrous roots are typical of monocots. Zea mays is a modification of
adventitious root for support also known as prop root. The structures or organs
developing in an unusual position. It is a root originating on the stem. The hanging
structure that support the tree are called prop roots. Root develop from tree branches
hang downward and ultimately penetrate the ground, thus provide support to heavy
branches. The functions is to absorb nutrient and also for strong support.
ii. Amaranthus sp.
- Amaranthus sp. is a tap root systems that have a main root that grows down
vertically, and from which many smaller lateral roots arise. Further development of
radicle into tap root. Tap roots penetrate deep into the soil and are advantageous for
plants growing in dry soils. Tap roots are typical of dicots. Amaranthus sp. is a
modification of adventitious roots for storage of food, which is fasciculated tuberous
roots. It is a cluster of adventitious roots for storage of food. This root have definite
shape.
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Observe the following root samples, illustrate and answer the question
Sample 1: Orchid
i. Name the type of root modification
- Aerial root
ii. What is the function of the white coating called velamen on the surface of the root?
- The function of the white coating called velamen on the surface of the root is
water proof barrier which is not permitting water loss.
Sample 2: Carrot
i. Name the type of root modification
- Tuberous roots
ii. What is the function of carrot root?
- The function of carrot root is for storage of food, starch and water.
Sample 3: Pandanus sp.
i. Name the type of root modification
- Adventitious/ Prop roots
ii. What is the function of the modified root?
- The function of the modification root of Pandanus sp. is to absorb nutrient and
also for strong support
Illustrate and determine the type of stem modifications for the following stem modification
samples:
i. Musa sp.
- Sucker
ii. Solanum tuberosum
- Tuber
iii. Zingiber officinale
- Rhizomes
iv. Asparagus sp.
- Cladode
v. Axonopus compressus
- Runner/ Stolon
vi. Imperata cylindrica
- Rhizomes
vii. Allium cepa
- Bulb
Observe the following stem samples and answer the questions:
Sample 1: Axonopus compressus and Imperata cylindrica
i. Discuss the differences between the stem morphology of the two samples.
- Axonopus compressus stem is a runners or stolons, while Imperata cylindrica
stem is a rhizomes. The horizontal stems of Axonopus compressus are grown
above the ground and beneath the surface ground but horizontal stems of
Imperata cylindrica grows below the ground. Axonopus compressus stem have
long and thin internodes and Imperata cylindrica the axillary buds at each nodes
and the scale-like leaves.
Sample 2: Zingiber officinale
i. Why is it categorized as stem and not as root?
- Zingiber officinale categorized as stem and not as root because it is a modified
storage stem called a rhizome. It contains buds and scale leaves (non- green
structures used for storage) and is used for vegetative propagation and also for
surviving through adverse conditions.
Sample 3: Musa sp.
i. Distinguished the stem morphology and explain which part of the plant is considered
as the stem.
- Sucker is a lateral branches originate from the basal and underground portion of
the main stem, grow horizontally beneath the soil and then come out obliquely
upward giving rise to leafy shoot. The psuedostem is the part of the plant that
looks like stem. This enlarged stem is very fleshy and filled with tons of water. It
is formed by tightly-packed, overlapping leaves that unravel themselves as the
plant grows taller. The psudeostem stops growing once all the leaves have
unraveled and the stem of the inflorescence reaches the top. Musa sp. have a
underground stem which is rhizome the true stem.
Sample 4: Solanum tuberosum
i. Why is it categorized as stem and not as root?
- Solanum tuberosum categorized as stem and not as root because it is a modified
stems called a tubers. It possess many qualification which is of stem and it is a
underground stem. It is called as modified stem because as it has scaly leaves, it
has nodes, internodes, buds and adventitious roots.
Observe, illustrate and determine the shape of trichomes on the samples given:
i. Durio zibethinus
- Stellate
ii. Imperata cylindrica
- Fimbriate
Illustrate and identify the type of compound leaf and describe the arrangement of leaflets
in each type of compound leaf:
i. Hevea brasiliensis
- Compound trifoliate. Compound leaves have 3 outward pointing boat-shaped
leaflets joined to a long stalk.
ii. Manihot esculentus
- Compound palmate. Leaflets are attached to the tip of the petiole. Palmately
divided into 5 to 9 lobes and alternate arrangement
iii. Cassia biflora
- Compound pinnate. Leaflets are attached along an extension of the petiole called
a rachis.
iv. Caesalpinia pulcherrima
- Compound bipinnate. The leaflets are also divided into leaflets. When the single
leaflets of the unipinnate leaf gets replaced with unipnnate leaves themselves
becomes bipinnate leaves. Leaflets are oval in shape.
v. Moringa oleifera
- Compound bipinnate. The leaflets are also divided into leaflets. Have 2 to 3
pinnate, with up to 6 pairs of pinnae. Leaflets are obovate in shape.
vi. Tamarindus indica
- Compound pinnate. Pinnately compound leaves with 10-18 pairs of leaflets, and
are slightly arching. Individual leaflets are small and oblong in shape.
vii. Averrhoa carambola
- Compound pinnate. Green leaves pinnate, alternate arrangement and each leaf has
about 7 - 9 leaflets.
Illustrate and identify the leaf arrangement of these leaf samples:
i. Ixora javanica
- Opposite
ii. Hibiscus rosa-sinensis
- Alternate
iii. Nerium oleander
- Whorled
iv. Leek
- Distichous
v. Mesua ferrea
- Opposite
